Electrical Cardiometry: A Reliable Solution to Cardiac Output Estimation in Children With Structural Heart Disease

Evaluation of Electrical Cardiometry for Measuring Cardiac Output and Derived Hemodynamic Variables in Comparison with Lithium Dilution in Anesthetized Dogs

Numerous cardiac output (CO) technologies were developed to replace the 'gold standard' pulmonary artery thermodilution due to its invasiveness and the risks associated with it. Minimally invasive lithium dilution (LiD) shows excellent agreement with thermodilution and can be used as a reference standard in animals. This study evaluated CO via noninvasive electrical cardiometry (EC) and acquired hemodynamic variables against CO measured using LiD in six healthy, anesthetized dogs administered different treatments (dobutamine, esmolol, phenylephrine, and high-dose isoflurane) impacting CO values. These treatments were chosen to cause drastic variations in CO, so that fair comparisons between EC and LiD across a wide range of CO values (low, intermediate, and high) could be made. Statistical analysis included linear regression, Bland-Altman plots, Lin's concordance correlation coefficient (ρ_c), and polar plots. Values of p < 0.05 represented significance. Good agreement was observed between EC and LiD, but consistent underestimation was noted when the CO values were high. The good trending ability, ρ_c of 0.88, and low percentage error of ±31% signified EC's favorable performance. Other EC-acquired variables successfully tracked changes in CO measured using LiD. EC may be a pivotal hemodynamic tool for continuously monitoring circulatory changes, as well as guiding and treating cardiovascular anesthetic complications in clinical settings.

Agreement between Electrical Cardiometry and Pulmonary Artery Thermodilution for Measuring Cardiac Output in Isoflurane-Anesthetized Dogs

In animals, invasive pulmonary artery thermodilution (PATD) is a gold standard for cardiac output (CO) monitoring, but it is impractical in clinical settings. This study evaluates the agreement between PATD and noninvasive electrical cardiometry (EC) for measuring CO and analyzes the other EC-derived hemodynamic variables in six healthy anesthetized dogs subjected to four different hemodynamic events in a sequential order: (1) euvolemia (baseline); (2) hemorrhage (33% blood volume loss); (3) autologous blood transfusion; and (4) 20 mL/kg colloid bolus. The CO measurements obtained using PATD and EC are compared using Bland-Altman analysis, Lin's concordance correlation (LCC), and polar plot analysis. Values of p < 0.05 are considered significant. The EC measurements consistently underpredict the CO values as compared with PATD, and the LCC is 0.65. The EC's performance is better during hemorrhage, thus indicating its capability in detecting absolute hypovolemia in clinical settings. Even though the percentage error exhibited by EC is 49.4%, which is higher than the standard (<30%), EC displays a good trending ability. Additionally, the EC-derived variables display a significant correlation with the CO measured using PATD. Noninvasive EC may have a potential in monitoring trends in hemodynamics in clinical settings.

Plasmalyte-A Based del Nido Cardioplegia Versus Plain Ringer Based del Nido Cardioplegia: Double-Blind Randomized Trial

Background: In this prospective randomized controlled trial, we compared the standard del Nido cardioplegia solution (SDN) with the modified del Nido cardioplegia solution (MDN) in which the base solution was the plain Ringer solution. Methods: A total of 80 patients aged < 12 years undergoing intracardiac repair of Tetralogy of Fallot were randomized into SDN (n = 39) or MDN (n = 41) groups. The primary outcome was a change in cardiac index (CI). Secondary outcomes were ventricular arrhythmias after the release of aortic-cross clamp, postoperative inotropic score (IS), time to peripheral rewarming, duration of mechanical ventilation, intensive care unit (ICU) length of stay, and hospital length of stay, and electron microscopic differences between the 2 groups. Cardiac Troponin-I, inflammatory markers tumor necrosis factor-α (TNF-α), and interleukin-L (IL-6) were measured. Results: Applying the noninferiority confidence interval approach, the difference between the changes in CI between the 2 groups was -0.093 L/min/m2 (95% CI: -0.46-0.27 L/min/m2) which was within the noninferiority threshold of -0.5 indicating that CI was similar in both SDN and MDN. Ventricular arrhythmias postclamp release (P = .91), IS (P = .09), duration of mechanical ventilation (P = .27), ICU length of stay (P = .50), hospital length of stay (P = .57), IL-6 (P = .19), TNF-α (P = .17), Troponin-I (P = .15), electron microscopy changes (P > .05) were not different between groups. Conclusion: MDN was shown to be noninferior to the SDN cardioplegia in terms of preservation of cardiac index. In addition, other metrics indicative of myocardial protection were similar between groups. In developing nations where SDN is not available or is expensive, MDN cardioplegia is an acceptable alternative.

Variability in the Hemodynamic Response to Fluid Bolus in Pediatric Septic Shock

OBJECTIVES

Fluid boluses are commonly administered to improve the cardiac output and tissue oxygen delivery in pediatric septic shock. The objective of this study is to evaluate the effect of an early fluid bolus administered to children with septic shock on the cardiac index and mean arterial pressure, as well as on the hemodynamic response and its relationship with outcome.

DESIGN, SETTING, PATIENTS, AND INTERVENTIONS

We prospectively collected hemodynamic data from children with septic shock presenting to the emergency department or the PICU who received a fluid bolus (10 mL/kg of Ringers Lactate over 30 min). A clinically significant response in cardiac index-responder and mean arterial pressure-responder was both defined as an increase of greater than or equal to 10% 10 minutes after fluid bolus.

MEASUREMENTS AND MAIN RESULTS

Forty-two children with septic shock, 1 month to 16 years old, median Pediatric Risk of Mortality-III of 13 (interquartile range, 9-19), of whom 66% were hypotensive and received fluid bolus within the first hour of shock recognition. Cardiac index- and mean arterial pressure-responsiveness rates were 31% and 38%, respectively. We failed to identify any association between cardiac index and mean arterial pressure changes (r = 0.203; p = 0.196). Cardiac function was similar in mean arterial pressure- and cardiac index-responders and nonresponders. Mean arterial pressure-responders increased systolic, diastolic, and perfusion pressures (mean arterial pressure - central venous pressure) after fluid bolus due to higher indexed systemic vascular resistance and arterial elastance index. Mean arterial pressure-nonresponders required greater vasoactive-inotrope support and had higher mortality.

CONCLUSIONS

The hemodynamic response to fluid bolus in pediatric septic shock was variable and unpredictable. We failed to find a relationship between mean arterial pressure and cardiac index changes. The adverse effects of fluid bolus extended beyond fluid overload and, in some cases, was associated with reduced mean arterial pressure, perfusion pressures and higher vasoactive support. Mean arterial pressure-nonresponders had increased mortality. The response to the initial fluid bolus may be helpful to understand each patient's individualized physiologic response and guide continued hemodynamic management.

Cardiac Output Measurement in Neonates and Children Using Noninvasive Electrical Bioimpedance Compared With Standard Methods: A Systematic Review and Meta-Analysis

OBJECTIVE

To systematically review and meta-analyze the validity of electrical bioimpedance-based noninvasive cardiac output monitoring in pediatrics compared with standard methods such as thermodilution and echocardiography.

DATA SOURCES

Systematic searches were conducted in MEDLINE and EMBASE (2000-2019).

STUDY SELECTION

Method-comparison studies of transthoracic electrical velocimetry or whole body electrical bioimpedance versus standard cardiac output monitoring methods in children (0-18 yr old) were included.

DATA EXTRACTION

Two reviewers independently performed study selection, data extraction, and risk of bias assessment. Mean differences of cardiac output, stroke volume, or cardiac index measurements were pooled using a random-effects model (R Core Team, R Foundation for Statistical Computing, Vienna, Austria, 2019). Bland-Altman statistics assessing agreement between devices and author conclusions about inferiority/noninferiority were extracted.

DATA SYNTHESIS

Twenty-nine of 649 identified studies were included in the qualitative analysis, and 25 studies in the meta-analyses. No significant difference was found between means of cardiac output, stroke volume, and cardiac index measurements, except in exclusively neonatal/infant studies reporting stroke volume (mean difference, 1.00 mL; 95% CI, 0.23-1.77). Median percentage error in child/adolescent studies approached acceptability (percentage error less than or equal to 30%) for cardiac output in L/min (31%; range, 13-158%) and stroke volume in mL (26%; range, 14-27%), but not in neonatal/infant studies (45%; range, 29-53% and 45%; range, 28-70%, respectively). Twenty of 29 studies concluded that transthoracic electrical velocimetry/whole body electrical bioimpedance was noninferior. Transthoracic electrical velocimetry was considered inferior in six of nine studies with heterogeneous congenital heart disease populations.

CONCLUSIONS

The meta-analyses demonstrated no significant difference between means of compared devices (except in neonatal stroke volume studies). The wide range of percentage error reported may be due to heterogeneity of study designs, devices, and populations included. Transthoracic electrical velocimetry/whole body electrical bioimpedance may be acceptable for use in child/adolescent populations, but validity in neonates and congenital heart disease patients remains uncertain. Larger studies in specific clinical contexts with standardized methodologies are required.

Modified ultrafiltration and postoperative course in patients undergoing repair of tetralogy of fallot

BACKGROUND

Expected benefits of modified ultrafiltration (MUF) include increased hematocrit, reduction of total body water and inflammatory mediators, improved left ventricular systolic function, and improved systolic blood pressure and cardiac index (CI) following cardiopulmonary bypass (CPB). This prospective randomized trial tested this hypothesis.

METHODS

Seventy-nine patients undergoing intracardiac repair of tetralogy of fallot were randomized to conventional ultrafiltration (CUF) + MUF (n = 39) or only CUF group (n = 40). The primary outcome was a change in hematocrit. Secondary outcomes were changes in peak airway pressures, ventilatory support, blood transfusions, time to peripheral rewarming, mean arterial pressure, central venous pressure, inotrope score (IS), and CI. Serum inflammatory markers were measured.

RESULTS

Baseline hematocrit was 50.6 ± 10.02 in the only CUF group whereas it was 43.9 ± 5.55 in the CUF + MUF group (p = .36). Following MUF, the CUF + MUF group had higher hematocrit (44.7 ± 0.50 g/dl) compared to the only CUF group (37.2 ± 0.49 g/dl), p ≤ .001 after adjusting for baseline hematocrit. Central venous pressure (mmHg) immediately following sternal closure was 9.27 ± 3.12 mmHg in the CUF + MUF group and 10.52 ± 2.2 mmHg in the only CUF group (p = .04). In the intensive care unit (ICU), they were 11.52 ± 2.20 mmHg in the only CUF group and 10.84 ± 2.78 mmHg in the CUF + MUF group (p = .02). Time to peripheral rewarming was 6.30 ± 3.91 h in the CUF + MUF group and 13.67 ± 3.91 h in the only CUF group (p = .06). Peak airway pressures in ICU were 17 ± 2 mmHg versus 20.55 ± 2.97 mmHg in CUF + MUF group & only CUF group, respectively, p < .001). Duration of mechanical ventilation was 6.3 ± 2.7 h in CUF + MUF group compared to 14.7 ± 3.5 h in the only CUF group (p = .002). IS was 11.52 ± 2.20 in the only CUF group compared to 10.84 ± 2.78 in CUF + MUFs group. Eight of 39 (20.5%) patients in the CUF + MUF group had IS > 10 compared to 22 of 40 (55%) patients in the only CUF group (p = .02). Serum Troponin-T and interleukin-6 levels were lower in the CUF + MUF group; TNF-α and CPK-MB were similar. ICU and hospital stay were similar.

CONCLUSION

Patients undergoing a combination of CUF and MUF had higher postoperative hematocrit, decreased duration of mechanical ventilation, lower need for inotropes and lower interleukin-6 and Troponin-T levels. This group had better postoperative outcomes. This study was registered with the Clinical trials registry of India (CTRI/2017/11/010512) before commencement.

Variability in the Physiologic Response to Fluid Bolus in Pediatric Patients Following Cardiac Surgery

BACKGROUND

Fluid boluses aiming to improve the cardiac output and oxygen delivery are commonly administered in children with shock. An increased mean arterial pressure in addition to resolution of tachycardia and improved peripheral perfusion are often monitored as clinical surrogates for improvement in cardiac output. The objective of our study is to describe changes in cardiac index, mean arterial pressure, and their relationship to other indices of cardiovascular performance.

OBJECTIVE

The objective of our study is to describe changes in cardiac index, mean arterial pressure, and their relationship to other indices of cardiovascular performance.

DESIGN, SETTING, PATIENTS, AND INTERVENTIONS

We prospectively analyzed hemodynamic data from children in the cardiac ICU who received fluid bolus (10mL/kg of Ringers-Lactate over 30 min) for management of shock and/or hypoperfusion within 12h of cardiac surgery. Cardiac index responders and mean arterial pressure-responders were defined as CI ≥10% and mean arterial pressure ≥10%, respectively. We evaluated the gradient for venous-return (mean systemic filling pressure-central venous pressure), arterial load properties (systemic vascular resistance index and elastance index) and changes in vasopressor support after fluid bolus.

MEASUREMENTS AND MAIN RESULTS

Fifty-seven children between 1 month and 16 years (median Risk adjustment after congenital heart surgery Model for Outcome Surveillance in Australia and New Zealand score of 3.8 (interquartile range 3.7-4.6) received fluid bolus. Cardiac index-responsiveness and mean arterial pressure-responsiveness rates were 33% and 56%, respectively. No significant correlation was observed between changes in mean arterial pressure and cardiac index (r = 0.035, p = 0.79). Although the mean systemic filling pressure - central venous pressure and the number of cardiac index-responders after fluid bolus were similar, the arterial load parameters did not change in mean arterial pressure-nonresponders. Forty-three patients (75%) had a change in Vasoactive-Inotrope Score after the fluid bolus, of whom 60% received higher level of vasoactive support.

CONCLUSIONS

The mean arterial pressure response to fluid bolus in cardiac ICU patients was unpredictable with a poor relationship between cardiac index-responsiveness and mean arterial pressure-responsiveness. Because arterial hypotension is frequently a trigger for administering fluids and changes in blood pressure are commonly used for tracking changes in cardiac output, we suggest a cautious and individualized approach to repeat fluid bolus based solely on lack of mean arterial pressure response to the initial fluid, since the implications include decreased arterial tone even if the cardiac index increases.

Electrocardiometry Fluid Responsiveness in Pediatric Septic Shock

Hemodynamic monitoring and categorization of patients based on fluid responsiveness is the key to decisions prompting the use of fluids and vasoactive agents in septic shock. Distinguishing patients who are going to benefit from fluids from those who will not is of paramount importance as large amounts of fluids used conventionally based on surviving sepsis guidelines may be detrimental. Noninvasive monitoring techniques for the assessment of various cardiovascular parameters are increasingly accepted as the current medical practice. Electrical cardiometry (EC) is one such method for the determination of stroke volume, cardiac output (CO), and other hemodynamic parameters and is based on changes in electrical conductivity within the thorax. It has been validated against gold standard methods such as thermodilution [Malik V, Subramanian A, Chauhan S, et al. World J 2014;4(7):101-108] and is being used more often as a point-of-care noninvasive technique for hemodynamic monitoring. EC is Food and Drug Administration approved and validated for use in neonates, children, and adults. A meta-analysis in 2016, including 20 studies and 624 patients comparing the accuracy of CO measurement by using EC with other noninvasive technologies, demonstrated that EC was the device that offered the most correct measurements. The article in the current issue of IJCCM by Rao et al. (2020) has extended the use of EC to categorize pediatric patients with septic shock into vasodilated and vasoconstricted states based on systemic vascular resistance and correlate the categorization clinically. The authors also studied the changes in hemodynamic parameters after an isotonic fluid bolus of 20 mL/kg was administered. This is a pilot prospective observational study of 30 patients, which has given an insight into physiological rearrangements following fluid administration in patients with septic shock. How to cite this article: Gupta D, Dhingra. Electrocardiometry Fluid Responsiveness in Pediatric Septic Shock. Indian J Crit Care Med 2021;25(2):123-125.

Cardiac output monitoring in paediatric cardiac surgery: a review

The aim of this review is to present the current options for cardiac output (CO) monitoring in children undergoing cardiac surgery. Current technologies for monitoring identified were a range of invasive, minimally invasive, and non-invasive technologies. These include pulmonary artery catheter, transoesophageal echocardiography, pulse contour analysis, electrical cardiography, and thoracic bioreactance. A literature search was conducted using evidence databases which identified two current guidelines; the NHS Greater Glasgow and Clyde guideline and Royal College of Anaesthetics Guideline. These were appraised using the AGREE II tool and the evidence identified was used to create an overview summary of each technological option for CO monitoring. There is limited evidence regarding the accuracy of modalities available for CO monitoring in paediatric patients during cardiac surgery. Each technology has advantages and disadvantages; however, none could be championed as the most beneficial. Furthermore, a gold standard for CO monitoring has not yet been identified for paediatric populations, nor is it apparent whether one modality is preferable based on the available evidence. Additional evidence using a standardised method for comparing CO measurements should be conducted in order to determine the best option for CO monitoring in paediatrics. Furthermore, cost-effectiveness assessment of each modality should be conducted. Only then will it be possible for clear, evidence-based guidance to be written.

Noninvasive Cardiac Output Monitoring Using Electrical Cardiometry and Outcomes in Critically Ill Children

Cardiac output (CO) measurement is an important element of hemodynamic assessment in critically ill children and existing methods are difficult and/or inaccurate. There is insufficient literature regarding CO as measured by noninvasive electrical cardiometry (EC) as a predictor of outcomes in critically ill children. We conducted a retrospective chart review in children <21 years, admitted to our pediatric intensive care unit (PICU) between July 2018 and November 2018 with acute respiratory failure and/or shock and who were monitored with EC (ICON monitor). We collected demographic information, data on CO measurements with EC and with transthoracic echocardiography (TTE), and data on ventilator days, PICU and hospital days, inotrope score, and mortality. We analyzed the data using Chi-square and multiple linear regression analysis. Among 327 recordings of CO as measured by EC in 61 critically ill children, the initial, nadir, and median CO (L/min; median [interquartile range (IQR)]) were 3.4 (1.15, 5.6), 2.39 (0.63, 4.4), and 2.74 (1.03, 5.2), respectively. Low CO as measured with EC did not correlate well with TTE (p = 0.9). Both nadir and mean CO predicted ventilator days (p = 0.05 and 0.01, respectively), and nadir CO was correlated with peak inotrope score (correlation coefficient of –0.3). In our cohort of critically ill children with respiratory failure and/or shock, CO measured with EC did not correlate with TTE. Both nadir and median CO measured with EC predicted outcomes in critically ill children.

Assessment of neonatal perfusion

Disorders of perfusion in newborn infants are frequently observed in neonatal intensive care units. The current assessment practices are primarily based on clinical signs. Significant technologic advances have opened new avenues for continuous assessment at the bedside. Combining these devices with functional echocardiography provides an in-depth understanding of perfusion and allows targeting therapy to the pathophysiology rather than monitoring and targeting blood pressure. This change in approach is guided by the fact that perfusion disorders can result from a number of causes and a single management approach might do more harm than good. This approach has the potential to improve long term outcomes but needs to be tested in well-designed trials.

The predictive value of the Pleth Variability Index on fluid responsiveness in spontaneously breathing anaesthetized children-A prospective observational study

BACKGROUND

In children, the preoperative hydration status is an important part of the overall clinical assessment. The assumed preoperative fluid deficit is often routinely replaced during induction without knowing the child's actual fluid status.

AIM

We investigated the predictive value of the Pleth Variability Index as a measure of fluid responsiveness in spontaneously breathing anesthetized children.

METHODS

Pleth Variability Index, stroke volume and Cardiac Index, measured by electrovelocimetry, mean blood pressure, and heart rate were recorded during anesthesia induction in 50 pediatric patients <6 years. Baseline values were compared to values recorded after administration of 10 mL/kg of Ringer's lactate and during two passive leg raising tests (before and after fluid administration). Fluid responsiveness was defined as an increase of ≥10% in stroke volume.

RESULTS

Only in fluid responsive patients, Pleth Variability Index values were higher before fluid administration than thereafter (21.4 ± 5.9% vs 15.0 ± 9.4%, 95% CI of difference 1.1 to 11.8%, P = .02). Pleth Variability Index values at baseline were higher in fluid responders (21.4 ± 5.9%) than in fluid nonresponders (15.3 ± 7.7%), 95% CI of difference 1.6 to 10.6%, P = .009. The area under the receiver operating curve indicating fluid responsiveness was 0.781 (95% CI 0.623 to 0.896, P = .0002), with the highest sensitivity (82%) and specificity (70%) at a Pleth Variability Index of >15% (Positive predictive value 2.71 (95% CI: 1.4 to 5.2)). Only in fluid responders, the Pleth Variability Index decreased during passive leg raising, while stroke volume increased.

CONCLUSIONS

The Pleth Variability Index may be of additional value to predict fluid responsiveness in spontaneously breathing anesthetized children. A significant overlap in baseline Pleth Variability Index values between fluid responsive and nonfluid responsive patients does not allow a reliable recommendation as to a cut off value.

Noninvasive Cardiac Output Monitoring in Newborn with Hypoplastic Left Heart Syndrome

OBJECTIVE

This study aimed to describe the first two cases of electrical cardiometry applied to newborn with hypoplastic left heart syndrome for hemodynamical assessment in the first days of life before surgical correction and see if this can help decision making process in these patients.

STUDY DESIGN

We describe two case series of two full-term newborn with hypoplastic left heart syndrome in the Neonatal Intensive Care Unit, ASST Grande Ospedale Metropolitano Niguarda, between December 2019 and January 2020.

RESULTS

Case 1 was persistently hemodynamically stable with prostaglandin E1 infusion at 0.01 mcg/kg/min, showing good capillary refill time, good diuresis, no difference between pre- and postductal values of oxygen saturation or blood pressure. Electrical cardiometry monitoring constantly showed cardiac output values higher than 300 mL/kg/min. Case 2 showed poor clinical condition needing prostaglandin E1 infusion up to 0.05 mcg/kg/min, intubation and septostomy associated with low cardiac output around 190 mL/kg/min. Once cardiac output has begun to rise and reached values constantly over 300 mL/kg/min, clinical condition improved with amelioration in oxygen saturation, diuresis, blood pressure, and blood gas analysis values. She was then extubated and finally clinically stable until surgery with minimal infusion of prostaglandin E1 at 0.01 mcg/kg/min.

CONCLUSION

This case highlights how hemodynamic information provided by electrical cardiometry can be used to supplement the combined data from all monitors and the clinical situation to guide therapy in these newborns waiting surgery.

KEY POINTS

· This is the first report of electrical cardiometry (EC) use in newborn with hypoplastic left heart syndrome (HLHS).. · In HLHS patients, it is impossible to measure cardiac output without being invasive.. · EC helps in guiding therapy in HLHS patients in a noninvasive way..

Electrical velocimetry has limited accuracy and precision and moderate trending ability compared with transthoracic echocardiography for cardiac output measurement during cesarean delivery: A prospective observational study

We aimed to evaluate the accuracy and interchangeability of stroke volume and cardiac output measured by electrical velocimetry and transthoracic echocardiography during cesarean delivery.We enrolled 20 parturients in this prospective observational study. We recorded the stroke volume and cardiac output using both methods and compared the values at seven specific time points. We analyzed the data using linear regression analysis for Pearson's correlation coefficients and Bland-Altman analysis to determine percentage errors. We conducted a trending ability analysis based on the four-quadrant plot with the concordance rate and correlation coefficient.We recorded 124 paired datasets during cesarean delivery. The correlation coefficients of the measured cardiac output and stroke volume between the two methods were 0.397 (P < .001) and 0.357 (P < .001). The 95% limits of agreement were -1.0 to 8.1 L min for cardiac output and -10.4 to 90.4 ml for stroke volume. Moreover, the corresponding percentage errors were 62% and 60%. The concordance correlation coefficients were 0.447 (95% CI: 0.313-0.564) for stroke volume and 0.562 (95% CI: 0.442-0.662) for cardiac output. Both methods showed a moderate trending ability for stroke volume (concordance rate: 82% (95% CI: 72-90%)) and cardiac output (concordance rate: 85% (95% CI: 78-93%)).Our findings indicated that electrical velocimetry monitoring has limited accuracy, precision, and interchangeability with transthoracic echocardiography; however, it had a moderate trending ability for stroke volume and cardiac output measurements during cesarean delivery.

Agreement of Cardiac Output Measurements between Bioreactance and Transthoracic Echocardiography in Preterm Infants during the Transitional Phase: A Single-Centre, Prospective Study

INTRODUCTION

Bioreactance cardiac output (CO) monitors are able to non-invasively and continuously monitor CO. However, as a novel tool to measure CO, it must be proven to be accurate and precise.

OBJECTIVE

To determine the agreement between CO measured with a bioreactance monitor and transthoracic echocardiography-derived left ventricular output parameters in preterm infants.

METHODS

This is a prospective observational study in 63 preterm neonates with non-invasive respiratory support, not requiring inotrope support. The infants underwent continuous bioreactance monitoring of CO and stroke volume (SV) and simultaneous transthoracic echocardiography every 6 h until 72 h of life.

RESULTS

The agreement between bioreactance and transthoracic echocardiography, for both SV and CO, was poor. The percentage error was 67.5% for SV and 71.6% for CO. The mean error was 60.4% for SV and 69.8% for CO. Bias was affected by numerous variables. After correcting for time, CO and SV bias were significantly affected by the presence of an open patent ductus arteriosus and the level of CO.

CONCLUSION

Bioreactance cannot be considered interchangeable with transthoracic echocardiography to measure CO in preterm infants during the transition phase. Agreement between bioreactance and other CO metrics should be assessed before concluding its accuracy or inaccuracy in neonates.

Accuracy and precision of non-invasive cardiac output monitoring by electrical cardiometry: a systematic review and meta-analysis

Cardiac output monitoring is used in critically ill and high-risk surgical patients. Intermittent pulmonary artery thermodilution and transpulmonary thermodilution, considered the gold standard, are invasive and linked to complications. Therefore, many non-invasive cardiac output devices have been developed and studied. One of those is electrical cardiometry. The results of validation studies are conflicting, which emphasize the need for definitive validation of accuracy and precision. We performed a database search of PubMed, Embase, Web of Science and the Cochrane Library of Clinical Trials to identify studies comparing cardiac output measurement by electrical cardiometry and a reference method. Pooled bias, limits of agreement (LoA) and mean percentage error (MPE) were calculated using a random-effects model. A pooled MPE of less than 30% was considered clinically acceptable. A total of 13 studies in adults (620 patients) and 11 studies in pediatrics (603 patients) were included. For adults, pooled bias was 0.03 L min^-1 [95% CI - 0.23; 0.29], LoA - 2.78 to 2.84 L min^-1 and MPE 48.0%. For pediatrics, pooled bias was - 0.02 L min^-1 [95% CI - 0.09; 0.05], LoA - 1.22 to 1.18 L min^-1 and MPE 42.0%. Inter-study heterogeneity was high for both adults (I² = 93%, p < 0.0001) and pediatrics (I² = 86%, p < 0.0001). Despite the low bias for both adults and pediatrics, the MPE was not clinically acceptable. Electrical cardiometry cannot replace thermodilution and transthoracic echocardiography for the measurement of absolute cardiac output values. Future research should explore it's clinical use and indications.

Non-invasive measurement of cardiac output in children with repaired coarctation of the aorta using electrical cardiometry compared to transthoracic Doppler echocardiography

OBJECTIVE

To evaluate the equivalence of the ICON^® electrical cardiometry (EC) haemodynamic monitor to measure cardiac output (CO) relative to transthoracic Doppler echocardiography (TTE) in paediatric patients with repaired coarctation of the aorta (CoA).

APPROACH

A group of n  =  28 CoA patients and n  =  27 matched controls were enrolled. EC and TTE were performed synchronously on each participant and CO measurements compared using linear regression and Bland-Altman analysis. The CoA group was further subdivided into two groups, with n  =  10 and without n  =  18 increased left ventricular outflow tract velocity (iLVOTv) for comparison.

MAIN RESULTS

CO measurements from EC and TTE in controls showed a strong correlation (R  =  0.80, p  <  0.001) and an acceptable percentage error (PE) of 28.1%. However, combining CoA and control groups revealed a moderate correlation (R  =  0.57, p  <  0.001) and a poor PE (44.2%). We suspected that the CO in a subset of CoA participants with iLVOTv was overestimated by TTE. Excluding the iLVOTv CoA participants improved the correlation (R  =  0.77, p  <  0.001) and resulted in an acceptable PE of 31.2%.

SIGNIFICANCE

CO measurements in paediatric CoA patients in the absence of iLVOTv are clinically equivalent between EC and TTE. The presence of iLVOTv may impact the accuracy of CO measurement by TTE, but not EC.

Impact of Obesity on Noninvasive Cardiac Hemodynamic Measurement by Electrical Cardiometry in Adults With Aortic Stenosis

OBJECTIVES

There are substantial potential benefits to noninvasive cardiac monitoring methods, such as electrical cardiometry (EC), over more invasive methods, including significantly reduced risk of complications, lower up-front and operational costs, ease of use, and continuous monitoring. To take advantage of these technologies, clinical equivalence to currently established methods must be determined. The authors sought to determine if the noninvasive measurement of cardiac index (CI) by EC was clinically equivalent to thermodilution (TD) in adult patients with aortic stenosis (AS).

DESIGN

This is a cross-sectional study comparing measurement devices in a single patient group.

SETTING

Single-center, university teaching hospital.

PARTICIPANTS

The study included 52 adult patients with aortic stenosis undergoing right heart catheterization.

INTERVENTIONS

Cardiac output (CO) was measured concurrently using EC with an ICON device and TD in 52 participants with AS. CI values were to determine the accuracy and precision of EC in reference to TD. Percentage error (PE) was used to assess their clinical equivalence. The participants were divided further into groups (normal and overweight/obese) based on body mass index and the analysis was repeated.

MEASUREMENTS AND MAIN RESULTS

CO measurement made by EC in adult patients with obesity or overweight was reduced significantly relative to TD. This was not observed in normal-weight adult AS patients. EC provided clinically equivalent measurements to TD for measuring CI in normal-weight adult AS patients (PE = 25.0%), but not for those adult AS patients with overweight or obesity (PE = 42.3%).

CONCLUSION

Overall, the ICON device produced lower CO and index measurements relative to TD in adult patients with AS. Overweight and obesity also significantly affected the relative precision and accuracy of the ICON electrical cardiometric device to measure CI in these patients.